154 lines
4.1 KiB
C
154 lines
4.1 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <hardware/hardware.h>
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#include <cutils/properties.h>
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#include <dlfcn.h>
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#include <string.h>
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#include <pthread.h>
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#include <errno.h>
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#include <limits.h>
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#define LOG_TAG "HAL"
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#include <utils/Log.h>
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/** Base path of the hal modules */
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#define HAL_LIBRARY_PATH "/system/lib/hw"
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/**
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* There are a set of variant filename for modules. The form of the filename
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* is "<MODULE_ID>.variant.so" so for the led module the Dream variants
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* of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
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*
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* led.trout.so
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* led.msm7k.so
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* led.ARMV6.so
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* led.default.so
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*/
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#define HAL_DEFAULT_VARIANT "default"
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static const char *variant_keys[] = {
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"ro.hardware", /* This goes first so that it can pick up a different
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file on the emulator. */
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"ro.product.board",
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"ro.board.platform",
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"ro.arch"
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};
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#define HAL_VARIANT_KEYS_COUNT (sizeof(variant_keys)/sizeof(variant_keys[0]))
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/**
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* Load the file defined by the variant and if successful
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* return the dlopen handle and the hmi.
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* @return 0 = success, !0 = failure.
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*/
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static int load(const char *id,
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const char *variant,
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const struct hw_module_t **pHmi)
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{
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int status;
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void *handle;
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struct hw_module_t *hmi;
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char path[PATH_MAX];
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/* Construct the path. */
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snprintf(path, sizeof(path), "%s/%s.%s.so", HAL_LIBRARY_PATH, id, variant);
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/*
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* load the symbols resolving undefined symbols before
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* dlopen returns. Since RTLD_GLOBAL is not or'd in with
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* RTLD_NOW the external symbols will not be global
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*/
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handle = dlopen(path, RTLD_NOW);
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if (handle == NULL) {
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char const *err_str = dlerror();
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//LOGW("load: module=%s error=%s", path, err_str);
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status = -EINVAL;
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goto done;
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}
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/* Get the address of the struct hal_module_info. */
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const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
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hmi = (struct hw_module_t *)dlsym(handle, sym);
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if (hmi == NULL) {
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char const *err_str = dlerror();
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LOGE("load: couldn't find symbol %s", sym);
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status = -EINVAL;
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goto done;
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}
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/* Check that the id matches */
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if (strcmp(id, hmi->id) != 0) {
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LOGE("load: id=%s != hmi->id=%s", id, hmi->id);
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status = -EINVAL;
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goto done;
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}
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hmi->dso = handle;
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/* success */
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status = 0;
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done:
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if (status != 0) {
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hmi = NULL;
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if (handle != NULL) {
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dlclose(handle);
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handle = NULL;
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}
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} else {
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LOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
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id, path, *pHmi, handle);
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}
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*pHmi = hmi;
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return status;
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}
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int hw_get_module(const char *id, const struct hw_module_t **module)
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{
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int status;
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int i;
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const struct hw_module_t *hmi = NULL;
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char prop[PATH_MAX];
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/*
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* Here we rely on the fact that calling dlopen multiple times on
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* the same .so will simply increment a refcount (and not load
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* a new copy of the library).
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* We also assume that dlopen() is thread-safe.
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*/
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status = -EINVAL;
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/* Loop through the configuration variants looking for a module */
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for (i = 0; (status != 0) && (i < HAL_VARIANT_KEYS_COUNT); i++) {
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if (property_get(variant_keys[i], prop, NULL) == 0) {
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continue;
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}
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status = load(id, prop, &hmi);
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}
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/* Try default */
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if (status != 0) {
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status = load(id, HAL_DEFAULT_VARIANT, &hmi);
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}
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*module = hmi;
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return status;
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}
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